Solving the mystery of ‘Oumuamua

New analysis suggests a natural origin for our first interstellar visitor, ‘Oumuamua

Early reports of ‘Oumuamua’s odd characteristics back in 2017 led some to speculate that the object could be an alien spacecraft, sent from a distant civilization to examine our star system.

First spotted by the Panoramic Survey Telescope and Rapid Response System 1 telescope located at the University of Hawaii’s Haleakala Observatory, the object defied easy description, simultaneously displaying characteristics of both a comet and an asteroid.

Astronomers named the object 1I/2017 U1 and appended the common name ‘Oumuamua, which roughly translates to “scout” in Hawaiian. Researchers had a few weeks to observe and collect data on ‘Oumuamua before it traveled beyond the reach of Earth’s telescopes.

New analysis however strongly suggests that ‘Oumuamua has a purely natural origin.

A research team led by scientists at the University of Maryland’s Department of Astronomy, along with input from collaborators from across the US and Europe, including the School of Physics and Astronomy’s Dr Colin Snodgrass, reported their findings in Nature Astronomy.

Observations have confirmed that ‘Oumuamua is red in color, has an elongated, cigarlike shape and an odd spin pattern—much like a soda bottle laying on the ground, spinning on its side. While it appears to accelerate along its trajectory—a typical feature of comets—astronomers are puzzled to find no evidence of the gaseous emissions that typically creates this acceleration.

There are a number of mechanisms by which ‘Oumuamua could have escaped from its home system. For example, the object could have been ejected by a gas giant planet orbiting another star. According to theory, Jupiter may have created the Oort cloud—a massive shell of small objects at the outer edge of our solar system—in this way. Some of those objects may have slipped past the influence of the sun’s gravity to become interstellar travelers themselves.

The research team suspects that ‘Oumuamua could be the first of many interstellar visitors, and look forward to analyzing data from the Large Synoptic Survey Telescope (LSST) in Chile, which is scheduled to be operational in 2022 to discover more on such visitors. The LSST is a major international project led by US astronomers, physicists and engineers. The UK is one of the major international partners in LSST, with UK involvement funded by the Science and Technology Facilities Council (STFC) and coordinated by astronomers at the University of Edinburgh.